In a typical radio frequency (RF) communications system, data may be processed at a transmitter device, modulated, filtered, amplified, and transmitted to one or more receiver devices. The transmitted signal typically experiences path loss, multipath interference, and other types of signal degradation before reaching the receiver devices. A receiver device receives the modulated signal, performs various types of conditioning, and demodulates the conditioned signal to recover the transmitted data. The signal conditioning typically includes low noise amplification, filtering, automatic gain control, frequency conversion, sampling, quantization, and so on. A tuner is a common circuit that performs many of these functions. One component of a tuner, such as a tuner for a satellite receiver, is a channel filter. For proper performance, channel filters usually need to be aligned.
Methods for aligning channel filters are known. An example of this is the master-slave solution. In this approach, one of the filter elements is duplicated and configured as an oscillator, which is then frequency-locked by a frequency-locked-loop (FLL) or similar. This first element is referred to as the master element. The control signal generated to tune the master is also used tune the filter (slave) in conjunction with the master. The master oscillator frequency and slave bandwidth are related by a correlation factor, which enables achieving a desired bandwidth by selecting an appropriate programming frequency. The master-slave method works satisfactorily but encumbers the radio with additional circuitry and power, such as the circuitry and power related to the additional filter element, the FLL, and loop filter components. The master-slave method may also introduce spurious amounts of noise due to the FLL in the output spectrum when the FLL is operating. Consequently, careful design and layout must be applied to minimize this effect.